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Apple CD SC - Not reading disks properly??

BadGoldEagle

BadGoldEagle

68020
Hi all

Happy new year to you guys and gals out there.

I picked up a CD SC last Friday. It's not in a great shape: there's a small crack on the top panel (not big enough to have caused serious damage to the drive) and it's pretty yellow. But that doesn't concern me right now. I'll fix the looks later.

When I first plugged it in, it would eject disks constantly, no matter what. I opened it up and cleaned the lens as suggested by CelGen and bear here. Now it will attempt to read them: amber light comes on when disk is inserted, and now it the disk will spin up as it should. Makes the right kind of noises too. It ticks every second.

But the drive access light (the amber one) won't flash at all when disk is spinning. Is it normal?

I don't have any SCSI Macs with me at the moment to test it. (I'm a student and the Macs are stashed at my folks' place 15mls away: that's a 1h15 drive, there's a lot of traffic). 

The big question is: The CD player in my Hi-Fi won't automatically start playing, I have to press "play" on the remote control before it jumps to track 1. Does the CD SC automatically starts playing an Audio-CD or do I need to tell it to through the CD control panel on a Mac?

I left the scsi circuitry at the back unplugged (SCSI ID selector, SCSI data cable and 'scsi audio'), that shouldn't have any effect since there's nothing plugged in to a Mac anyway. I hooked up my headset to the 3.5mm jack, I can hear some static when I turn the volume knob so I think the headphone board is okay. Same thing occurs when I connect the phono plugs at the back to my HiFi.

The problem is I don't know if it works, maybe it does? But the Owner's manual's nowhere to be found. And the service manual isn't really helpful.

If you have the answer, I'd be happy to hear it. Thanks!

 
Hi lambert,

Probably the CD SC is waiting a signal from the SCSI side to keep on going, probably won't work as a standalone device.

Just my two cents, but that's the way the 20 SC is working anyway.

 
Yea these dont work as standalone. Neither does my CD 300i. 

But, If the disk spins up, you hear a bit of hissing/servo noise on startup, and then the disk spins and holds steady doing absolutely nothing but spinning, and no servo noise afterwords it should be fine. the Servo processor does a focus lock, then tracking lock after spinning up the disc. It reads the TOC, and then once it determines the disc is present and valid, it sits waiting for command. 

It should spin for 15 to 30 seconds and then slowdown/stop. Its waiting for command. After some period of inactivity, the servo processor will go to sleep spinning down the disc.

But if the disc spins up and you hear continuous repeated seeking noises over and over again, or "ticking/clicking" and then hissing over and over, the laser pickup is bad or weak. 

It should spin up, make a "squirrelly hiss" for a bit, couple minor hiss-ticks and then sit idle spinning no more hissing. Thats normal. 

 
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Ah. Well here's what it sounds like after one minute or so. It's not that loud in real life. The microphone was right against the slot.

Cd_Sc.mp3

The pickup arm is probably bad then... Is there a way to bring it back to life? A potentiometer maybe?

When I took the drive apart, I tried to move the arm a bit. It was completely stuck (unit was off of course).

It seems to suffer from the same symptoms as the 400k floppy drives. Perhaps there's an optical sensor somewhere in this drive? You know about the click of death, right? At startup, the FDD head is moving towards the rear of the drive until a sensor is activated. If it's not activated it hits the metal cage and does not stop there, causing the famous tick tick tick noise aka Click of Death

Maybe it's the same problem? After all, both units were made by Sony in the 80s.

Found a picture of the mechanism: From Samuel M. Goldwasser

cdu8001.gif.e4b6078727670165a5a27802ac3dc002.gif


I'll open it up again tomorrow to check if the arm is moving or not.

Edit: Hang on, maybe the Shipping Lock's engaged???

 

Attachments

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That sound is normal. the servo noise is a little bit louder than it should be, might be time to start looking at caps. But that is a normal sound. the CD is sitting there idle. 

that "hissing" sound CD players and CD-ROM drives make is the constant error-correction pulses being sent to the two coils in the optical-pickup or laser head from the servo amplifier/drive. 

When you hear this "hiss" drop out and you get a click-click-click over and over and hiss kicks back in = Thats bad... 

 
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Thanks techknight!

I guess next thing is to try it out. Got the software. All I need now is my SE/30

Will report back next Saturday.

 
Being an early 90's Sony product my money is on our friend the SMD lytic cap being at fault. I have a slightly later Sony caddy loader in my IBM PS/2 and it would inject, spin and eject discs but wouldn't read them. A few of the later AppleCD drives that were rebranded from Sony also have the same problems. There was a number of leaking SMD lytics inside that needed to be replaced. It's been years since I've cracked mine open to confirm but my money is on this being the cause.

 
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CD 150 and up, to be more precise.

The original CD SC and CD SC plus use a drive so weird I've never seen them used anywhere else, likely inpart because they are not your standard half-height 5 1/4" form factor optical drive.

 
CelGen said:
Being an early 90's Sony product my money is on our friend the SMD lytic cap being at fault. 
Click to expand...
I don't think this one has SMD caps (unlike the SC Plus), but it's got quite a few radial ones all right. As far as I can tell, they're okay for now. 

The CD mechanism in the CD SC (not Plus) is a Sony CDU-8001. (see top and bottom view of the insides a couple of posts above.) Can't get much more info.

I got the CD spinning by cleaning the lens. Apparently this drive won't spin the disk if the lens is dirty and will eject it if that's the case. Mine seems to work now, of course I can't test right now, but fingers crossed, it'll work. At least it won't eject the disks anymore.

Will report back with the results tomorrow. 

 
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don't think this one has SMD caps (unlike the SC Plus), but it's got quite a few radial ones all right. As far as I can tell, they're okay for now. 
Click to expand...
Depends,  really. If it's those tiny radials than I've run into them failing before in late 80's and early 90's products. Even more recent if they were in extremely hot (LCD panel) environments.

 
Yeah it works!!

I've got a little treat for you guys/gals, it's still Christmas around here.


PS: it's the only cd I could find. Damn, I hadn't realised CDs were so obsolete these days.

 
laserdiscs? I never owned any so I never thought about it. plus laserdisc was wayyyy before my time. 

I could have said Beta, U-Matic, VHS, etc... 

Even though CDs and optical drives in general are becoming obsolete, from a design and operating standpoint it still fascinates the hell out of me. it is a very very mathematically complicated system. 

When the CD player came out in the 80s, it was well ahead of its time electronically. 

 
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